BAGHDAD, Iraq, March 29 — Facing growing pressure from the Bush administration for him to step down, Iraqi prime minister Ibrahim al-Jaafari today vigorously asserted his right to stay in office and warned the Americans against undue interference in Iraq's political process.

Gen. Peter Pace, chairman of the Joint Chiefs, at the Pentagon with Defense Secretary Donald H. Rumsfeld, explaining a map of the mosque compound assaulted by Iraqi and American troops on Sunday.

Mr. Jaafari also defended his recent political alliance with radical anti-American Shiite cleric Moktada al-Sadr, now the prime minister's most powerful backer, saying in an interview that Mr. Sadr and his thousands-strong militia were a fact of life in Iraq and need to be accepted into mainstream politics.

Mr. Jaafari said he would work to fold the country's myriad militias into the official security forces and ensure that recruits and top security ministers abandon their ethnic or sectarian loyalties.

The existence of militias has emerged as the greatest source of contention between American officials and Shiite leaders like Mr. Jaafari, with the American ambassador arguing in the past week that militias are killing more people than the Sunni Arab-led insurgency. Dozens of bodies, garroted or executed with gunshots to the head, turn up almost daily in Baghdad, fueling sectarian tensions that are pushing Iraq closer to full-scale civil war.

The embattled Mr. Jaafari made his remarks in an hour-long interview with The New York Times at his home, a Saddam Hussein-era palace with an artificial lake in the heart of the fortified Green Zone. He spoke calmly, relaxing in a black pinstripe suit in a ground-floor office lined with books like the multi-volume "The World of Civilizations."

"There was a stand from both the American government and President Bush to promote a democratic policy and protect its interests," he said, sipping from a cup of boiled water mixed with saffron. "But now there's concern among the Iraqi people that the democratic process is being threatened."

"The source of this is that some American figures have made statements that interfere with the results of the democratic process," he added. "These reservations began when the biggest bloc in Parliament chose its candidate for prime minister."

The bookish, soft-spoken Mr. Jaafari is at the center of the deadlock in talks over forming a new government, with the main Kurdish, Sunni Arab and secular blocs in the 275-member Parliament staunchly opposing the Shiite bloc's nomination of Mr. Jaafari for prime minister. Senior Shiite politicians said Monday that the American ambassador, Zalmay Khalilzad, had weighed in over the weekend, telling the leader of the Shiite bloc that President Bush did not want Mr. Jaafari as prime minister. That was the first time the Americans had openly expressed a preference for the post, the politicians said, and it showed the Bush administration's acute impatience over the stagnant political process.

Badr wants to legalize their death squads and now Sadr is saying the prime minister is his prime minister. Of course, now the Americans want to pick who ruins Iraq, not even aware that would just make that person a puppet. But why notice minor things like that now.